Subtropical in the Koppen and Trewartha classification is defined as a region, where at least eight months has an average temperature of more than 10 °C, but the coldest month has an average temperature of less than 18 °C. The individual subtypes then differ in their annual precipitation distribution. In Trewartha classification there is a condition of maximum annual precipitation of 900 mm.

In general the subtropical climate is usually found in areas polewards from the tropical zones. It can also be found inside tropical zones at places with higher altitude. Typical are for example citrus trees or palm trees.

The Cs subtype in the Trewartha classification represents a subtropical climate with dry summer, sometimes referred to as the Mediterranean climate. It is characterized by hot and dry summers and mild winters, during which most of the precipitation is observed. High pressure is the dominating factor in the summer, when precipitation is very small and if there is some, it is usually in the form of very short, but intense thunderstorms. In the winter it can sometimes snow, especially at higher altitudes, but in general the winters are mild.

This climate type is most common in western coasts of continents in the middle latitudes, for example it includes areas on the West coast of the U.S. such as California, Southern Europe or Southwest tip of Australia.

• warm summer: warmest month with average temperature between 18 and 23 °C
• mild winter: coldest month with average temperature between 10 and 18 °C